Project Summary This career enhancement award will facilitate the transition of an established, federally-funded adolescent relationship health intervention researcher to the field of autism spectrum disorder (ASD) research. There are now approximately 450,000 youth with ASD between the ages of 16-24 years old in the U.S., and 50,000 more turning 18 each year. There is a tremendous need for evidence-based interventions for transition-age youth and young adults with ASD to promote healthy peer relationships. Autism is characterized by difficulty in social relations, and many individuals with ASD struggle to establish, maintain and manage peer relationships during the transition to adulthood. Moreover, individuals with ASD can experience high rates of peer victimization, including dating and sexual violence victimization. Evidence-based, cost-effective interventions that support the development of healthy peer relationships are urgently needed. The proposed training and research plan will equip the applicant with the skills, experience and collaborative relationships necessary to launch a line of research to evaluate the impact of psychosocial interventions to promote healthy relationships for transition- age youth with ASD. Training objectives are: (1) ASD topical knowledge, (2) evidence-based intervention development for transition-age youth with ASD, and (3) statistical methods for clinical trials and for analyses consistent with the NIMH experimental therapeutics model. Mentors include experts in research with ASD transition-age youth and young adults, and intervention development for ASD. The research will achieve two specific aims. Aim 1 is to conduct formative research that will inform the content of the new Healthy Peer Relationships on the Spectrum (HEARTS) online group intervention, and improve measurement instruments. Aim 1 will be achieved through qualitative research with 15 youth with ASD (ages 16-22 years old, average or high IQ), 15 parents, and 15 research and practitioner experts (N=45). Aim 2 will assess the feasibility of implementation of the HEARTS intervention and intervention research procedures. Aim 2 will be achieved through a pilot randomized controlled trial (RCT) in which N=48 youth with ASD, ages 16-22 years old, average or high IQ, will be randomized to either the HEARTS intervention or a comparison condition. Quantitative assessments will be made at baseline and 3 months, and qualitative data will enrich findings. RCT outcomes are feasibility-related: feasibility of recruitment, delivering the intervention, retaining participants, fidelity, burden of assessments, acceptability, and human subjects issues. As per the experimental therapeutics model, target mechanisms and clinical endpoints have been identified. While the goal of the pilot RCT is not to test hypotheses, the research will test the feasibility of assessing clinical endpoints including depression, social anxiety, and experiencing psychological, physical, and sexual aggression and/or stalking. The research will yield preliminary psychometric information on measures. A targeted enrollment scheme will ensure that research participants are racially/ethnically diverse, and of all genders.